Liquid herbicidal compositions are well known. They are either prepared from solid compositions by contacting with appropriate solvents or are made available in the ready-to-use liquid form. The activity of such composition and consequently their efficacy in weed control is largely dependent on the bioavailabilty of the actives in the target weeds. Additionally, conventional liquid herbicidal compositions sometimes tend to be unstable leading to settling down of the ingredients. Depending on the nature of the actives various stability enhancing agents are added to such conventional herbicidal compositions. Such agents include surfactants.
It is known from the art that organophosphorous compounds such as glufosinate possess a good and broad activity against weeds of many botanical families. The ammonium salt of these compounds is particularly important. They are usually formulated as aqueous solutions. Both spreadability and adhesion are major criteria for agrochemical formulations which are sprayed onto waxy plant surfaces. The ability to spread quickly and uniformly on the waxy part of plant surfaces enables quick uptake of the agrochemical resulting in greater bioavailability of the active molecule to the plant. In case of aqueous formulations of herbicides such as glufosinate, both spreadability and adhesion improves the effect of the herbicidal activity on the weed.
U.S. Pat. No. 5,491,125 (Albrecht et. al) discloses the use of several class of surfactants which may be used to formulate organophosphorus based herbicides. The patent however, discloses in examples that use of certain surfactants results in a cloudy formulation, which is known to occur due to phase separation within the formulation. The formulations disclosed here are not generally stable.
U.S. Pat. No. 6,887,830 (Stridde et. al.) discloses that the bioefficacy of amine based surfactants can be enhanced by adding sulfosuccinate based surfactants. The volume of surfactants needed is between 25 to 45% of the total composition out of which, 45% to 60% by mass of the surfactant component comprises the amine based surfactant which is a fatty amine alkoxylate. The patent discloses the preparation of such sulfosuccinate esters, with acid and hydroxy-bearing hydrophobes such as alcohol alkoxylates resulting in a mixture of alkoxylated mono and diesters of sulfosuccinate. Due to the presence of such hydrophobes it often leads to haziness in aqueous medium thereby indicating incompatibility of these surfactants with electrolytic agrochemicals in aqueous formulations.
U.S. Pat. No. 3,527,593 (Bland et. al) discusses the amine oxide surfactants and their spreadability when combined with alcohols.
US 2012/0172229A1 (Nguyen et. al) discloses the use of a (C3-C8)monoalkyl sulfosuccinate ester as a compatibilizing agent along with a high load of pesticides and other surfactants.
None of the compositions in the prior art, however, provide a composition that is sufficiently stable, environment friendly as well as shows significant weed control. There is, therefore, a need in the art for a liquid herbicide composition that is stable and demonstrates excellent weed control apart from being environmentally benign.